92 MX-3 Idles Rough, Quits when I accelerate

Hi There Everyone ...

I recently purchased an MX-3 1.8 5spd for my son. The car starts up fine, idles a little rough ... the idle seems to go up and down on its own, however will usually stay running. When you accelerate, the car just quits.
I'm just wondering if anyone has an idea as to where to begin? I know that my best bet is to have a mechanic hook it up to the computer, but with the way its running it won't move out of the driveway!!
I thank you all in advance for any help you can offer!!

~Dee~

I would check your intake for any intake leaks. Such as a bigass hole in the 'accordian' tube located after the VAF (Volume Air FLow meter. THe black thing that reads JE50 on it). Also make sure that there is a wire connecting to the VAF securely. Often what causes an un-even idle is unaccounted-for air.

Check and double check all vaccum hoses. I heard to use propane on the hoses to see if there are any leaks.

Are you getting any Check Engine light? If so check the codes by following the procedure found on mx-3.com:

Locate and open the "Diagnostic" box under the hood. It's by the firewall. Below is shown a representation of the pins inside the Diagnostic box:


The pins labelled "TEN" (which stands for "Test ENgine" by the way) and GND (ground) are the pins of interest. Make sure the ignition is OFF and use a paperclip to jumper the TEN and GND pins together.

Turn on the ignition (do not start the car) and watch the CEL. After about 4-seconds, it will begin to flash any codes that may be stored. If there are no codes stored, the CEL will not flash (it will go out.)

Malfunction codes are generally 2-digit affairs although Mazda decided to get tricky. They include 2-digit codes that involve '0' (zero) as a digit. Code 02 is one example. Code 10 is another.

The codes are broken into a 10s digit and a 1s digit. The 10s digit is flashed first, followed by the 1s digit. The digits are distinguished by the length of time they flash the CEL. 10s digits flash the CEL on for 1.2-sec while 1s digits flash the CEL for 0.4-sec. Digits that are '0' (zero) flash the CEL exactly zero times.

The diagram below illustrates graphically how two typical malfunction codes might be flashed out.


Note how the presumably single-digit code '3' flashes the CEL for short-pulses only. This indicates the 10s digit is zero for this code.

List of codes and what they correspond to:

02 'NE2' crankshaft position sensor

03 'G' camshaft position sensor

04 'NE1' camshaft/crankshaft position
sensor

05 Knock sensor

08 Volume Air Flow sensor (VAF)

09 Coolant temperature sensor (CTS)

10 Intake air temperature sensor (IAT)

12 Throttle position sensor (TPS)

14 Barometric pressure sensor

15 LHO2S inactivation error

16 Exhaust gas recirculation (EGR) system

17 LHO2S inversion error

23 RHO2S inactivation error

24 RHO2S inversion error

25 Fuel pressure regulator control solenoid

26 Canister purge solenoid

28 EGR vacuum solenoid

29 EGR vent solenoid

34 Idle air control (IAC) solenoid

41 VRIS #1 solenoid

46 VRIS #2 solenoid

I would suggest going to mx-3.com for any further tips. THose guys know their stuff and all of us on this board are also registered there anyways. ;) Good Luck and keep me posted. Ill do my best to help.

btw the VAF is located on the intake right after the 'accordian' tube, in case you didnt know. ;)

MX3MAN ....

I can't thank you enough for the info!! I will deffinatly check out the MX-3 site. I was thinking it was an air problem, but wasn't completely sure. Would the oxygen sensor have any of these symptoms? Someone had told me to replace that ... but I don't want to jump into buying things that I don't need!
I'll make a point of looking for any obvious possible leaks. I know this has to be something simple!!
Thanks again, and I will keep you posted!!

~Dee~

no bad o2 won't do that..when they go your car just richen up a bit to prevent a lean condition

Hey MX3MAN thanks for all the info. I found it useful once I found the vacum leak that controlled the sensors. Now I found I have an EGR problem. I have a 95 Mazda MX3 1.6 L4 if you know any info I could greatly appreciate it. Thanks Jon

no problem..

Unfotunately, I dont know much about the 4 bangers.. try http://www.mx-3.com in the forums... TONS of info and very smart people there.